258 Dr George Buist on the 



those continental streams the country would be doomed to a state of per- 

 petual sterility — a few showers occurring in September being all the rain 

 that ever fulls in the neighbourhood. 



In the great Andes plateau in South America, stretching from the 

 Tropic of Cancer northwards for the space of 1200 miles, with a mean 

 breadth of 200, is a depression with a surface area equal to about that of 

 the Red Sea. This basin is about 12,000 feet above the level of the ocean, 

 the principal lake being that of Titicaca, occurring at an altitude equal to 

 that of Teneriife. It is about 26,000 square miles in area, and 700 feet 

 in depth. The scenery and verdure around seem in the highest degree rich 

 and beautiful, and the climate delightful. 



There are no continental river basins or valleys of any extent in any 

 part of Europe, the rains being sufficiently abundant, and evaporation 

 moderate enough, to enable the moisture which falls to accumulate in the 

 valleys till it forms lakes which discharge their waters into rivers, all 

 finding their way to the sea ; and the only depressions at all resembling 

 those under consideration, and of the same character, though of inconsi- 

 derable depth, and due, doubtless, to the same causes, are those in Hol- 

 land — the Lake Harlaem and the Zuyder Zee. 



We know so little of Central Africa that we are unable to speak of its 

 characteristic features with anything like certainty. From the magnitude 

 of some of the lakes known to exist, and the streams made mention of, 

 compared to the scantiness of the discharge of fresh water into the sea, 

 there is reason to believe in continental river basins great in number and 

 vast in size. The only depressions well known to us are those of the lake 

 Mareotis, on the Mediterranean shore, close by Alexandria, of the Bitter 

 Lakes in the Isthmus of Suez, like Mareotis, and the Natron Lakes, all 

 in Lower Egypt, and Lake Assal, off the shores of the Gulf of Aden, a 

 short way into Abyssinia. The first of these depressions has probably 

 been seen by most of those who have made the journey overland. It seems 

 to have been formed by a sinking of the Delta up to close upon the shore, 

 where a barrier was left ; it is at its lowest some six or eight feet below 

 the Mediterranean, and occupies an area of about 5000 square miles, being 

 about 30 across and 150 in length. It seems to have been a fresh water 

 marsh in Pliny's time, when the Nile was admitted to it by canal, and it 

 was transformed into a lake. By the end of last century it had become 

 nearly dried up, and its ancient bed, remarkable for its fertility, was irri- 

 gated by canals from the Nile. In 1801, during the siege of Alexandria, 

 then held by the French against the English, a letter was found on the 

 body of General Roitz, expressing alarm lest the sea should be admitted 

 to the lake Mareotis, and the town deprived of fresh water. The hint 

 was taken by the British General, and the barrier cut across. The vast 

 plain was immediately submerged, the sites of 300 villages were flooded, 

 and one of the most fertile and profitable portions of Egypt — the very 

 garden of the Nile — reduced to sterility. For 10 or 15 miles the railway 

 skirts or traverses the margin of the lake, so as to bring it within the view 

 of overland passengers betwixt Europe and the East. Near the period 

 of low Nile the waters of the lake are concentrated by evaporation up close 

 to the point of saturation, and vast sheets of salt of dazzling whiteness, 

 the reflection of which is seen in the sky far out at sea, spread over the 

 shallows round its borders, to be redissolved when the waters of the Nile 

 are admitted during the inundation. A benevolent government or enter- 

 prising people would speedily pump out the brine by steam, and restore 

 the soil to its wonted fertility by repeated washings from the Nile. As 

 matters at present stand it is likely to remain forages, until the Nile silts 

 it up to the level of the sea, a monument of the cruelties wars of aggres- 

 sions inflict or compel, and of the apathy and indifference of an admini- 



